Effect of the air-conditioning system on the fuel economy in a gasoline engine vehicle

The air-conditioning system is the single largest auxiliary load on a vehicle. This implies that the air-conditioning system is the key component among all accessories which causes the fuel economy to deteriorate. Therefore, it is important to verify the primary parameters of the components of the air-conditioning system which affect the fuel consumption. This paper presents the effect of each component of the air-conditioning system on the fuel consumption of a conventional gasoline engine vehicle operating at various engine speeds. It was found that air-conditioning operation increased the fuel consumption by 90% maximum compared with the operation without air-conditioning during the idling condition. As the vehicle speed increased, the portion of the fuel consumption due to the compressor of the air-conditioning system increased, while the portion of the fuel consumption due to the alternator decreased. Other components such as the blower, the cooling fan and the clutch maintained nearly constant portions of the torque distribution from the alternator irrespective of the vehicle speed.